Heretofore, a fuel cell system including a fuel cell which receives the supply of a reactive gas (a fuel gas and an oxidizing gas) to generate a power has been suggested and put to practical use. In the fuel cell of such a fuel cell system, and a fuel off gas circulation channel, an impurity gas such as nitrogen or carbon monoxide generated during power generation, and a water content are accumulated with an elapse of time. To discharge such a gas and water content from the system, a technology (a purge technology) is suggested in which the circulation channel (or a discharge channel connected to this circulation channel) is provided with a gas discharge valve and a water discharge valve, and these gas and water discharge valves are controlled to open and close, whereby the accumulated gas and water content are discharged after each predetermined time.
Moreover, at present, a technology is suggested in which a purge valve for performing the gas discharge/water discharge is controlled to open and close in a low-temperature environment, whereby the low-temperature start performance of the fuel cell system is improved. For example, a technology is suggested in which in the low-temperature environment, an ignition switch is turned on, and then the purge valve is once opened to perform purge processing. Afterward, in a temperature raising process, the purge processing is prohibited until the fuel cell is warmed up, whereby the temperature drop of the fuel cell due to the supply of a new hydrogen gas is suppressed (see Japanese Patent Application Laid-Open No. 2004-178901).